A 6-inch Newtonian reflector that gives apochromatic refractor quality images!
Orion sells a 6-inch f/8 optical tube assembly, which is a great scope design for planetary use. However, it comes with
a diagonal mirror that is just a little too large and a standard four-vane spider. I removed the spider and the 1.3-inch diagonal mirror
that came with the scope and installed a smaller, 1.1-inch secondary mirror. It is well known that a smaller secondary obstruction
will yield higher contrast images. I made the spider by bending a piece of brass into a circle and bolting it to the side of
the tube. The diagonal mirror is simply glued to the end of a dowel rod that is screwed onto the brass ring. The whole thing is
sprayed with flat black paint.
The improvement in image quality was fantastic. Bright objects no longer had diffraction spikes and the subtle contrast on
the surface of Mars and other planets was noticably better. At a recent star party, my little six-inch reflector out-performed several
larger scopes, including a ten-inch Newt.
The total weight of the finished tube assembly: 10 pounds. This means I only need one 10-pound counterweight on the mount.